Radical bow surgery (Martin Hunter)

[toolmaker]

I'm a compulsive tinkerer, so when I couldn't get my 29" 2216s with 165 gr. points tuned out of my 60# Martin Hunter, my knee-jerk reaction was to fix the bow.  The arrows are stout, but with the 165s, the spine seems good based on the 1" verticle tear I was unable to improve upon with nocking point adjustments.  Curiously I got the best flight in a range from 3/4"-1" above square.  I reasoned that the lower limb is too stiff (tillering seems OK), so I decided to build up the arrow shelf.  I also sanded the window past centershot to accomodate even stouter missiles (should the need arize).  That got the tear down to about 3/4" in a range of 5/8"-7/8" above square.  I've also tried brace height adjustments from the low end of 7" to 7 5/8" with no noticeable impact.  I shoot three under, and that gives best and most consistant results, but I can still see my tails wagging at short distances, and expect  poor flight from broadheads.  I believe a very slight weakening of the lower limb may allow a lower nocking point and cure the porpoising.  Boyers please advise.

[Dano]

Do you know how to measure for positive tiller?

[toolmaker]

My understanding is that I measure from fadeout to string.  I must confess I didn't do this; A fellow at the pro shop checked and said it was OK.  What, exactly should I look for, and if the tillar can be adjusted, is it something a new and aspiring boyer can do?

Thanks

[Dano]

I just have to say, it isn't every one that tunes a bow to a set of arrows as drastically as you. Are you shooting three under because of the bows performance, or have you always shot three under? Most bows are not built for three under shooters, but adjusting the knocking point will usually fix poor arrow flight. If you feel the need, weakening the lower limb might help, but you just risk messing the tiller up completely, I think. How's that for words of wisdom?

[Apex Predator]

You need to scrap the paper tuning unless you are ready for the olympics.  I bet only 1 in a 1,000 shoot well enough to find meaningful results.  Try bare shaft tuning instead.  Much easier to read for us trad guys.

[toolmaker]

Actually, I don't think the arrows are the problem.  I also understand that the Hunter typically requires a very high nocking point.  I will venture the hypothesis that this is just a design flaw that Martin chooses not to address. I'm not positive it's tiller, but In the case of my bow it's enough that I can't fix the porpoising with simple nocking point adjustments.  I just measured the tiller at the fade-outs.  The UL is 7 7/8 the LL is 7 3/4.  Does that seem right?  

I prefer shooting three under as it puts my eye closer to the action, but I tried one over to try and correct the tuning issue, and it got worse.

As for bare shaft tuning, I have tried it, and found there is no signifigant difference within the range of the first and biggest wobble of an out of tune arrow.  It works on the same principal as paper tuning with the target acting as the paper.  When I shot a compound (gasp!) I found once I got a bullet hole through paper, my broadheads (not mechanicals) went to my point of aim and grouped nearly as tightly.  I try to be objective about these things.  Those have been my observations, not my opinions.  I hope to form an opinion someday, maybe.

Thanks, Dano and A.P. You guys are awesome, and much more genteel than the guys on some of the other forums.  They can be downright nasty.

 

 

Cave-art rocks.

[Jason Scott]

It could be the way you are releasing with your fingers. Twist on the string or more pressure on the wrong fingers at full draw. Make sure you are not plucking. Make sure you are not over drawing. That can cause torqueing and twisting before during and after the shot. Changing arrows can make a world of difference, more times than not they are the problem if shooting form is ruled out.

[Dano]

I would try going even higher with the brace height, Martin recommends up to 7.75 but you might try even higher, also with that you might try adjusting the knocking point in conjunction. The tiller is very close, I wouldn't mess with that. Be patient you'll get there.

[toolmaker]

Hi guys,

Haven't been able to try anything in a couple days.  Weather's been crappy.  I will try more brace height, and be more mindful of my form and release.  I'll report back with the results.

Thanks all.

 
 

 

The fix is almost in; the fifth column has taken over Washington.  Your liberty and livelyhoods are next.